Processing method of paper-making pulping black liquor

A papermaking pulping black liquor and treatment method technology, which is applied in the chemical industry, can solve the problems of small treatment volume, large amount of resin consumption, and difficult separation operation, and achieve the effects of low cost, wide applicability, and simple process

Inactive Publication Date: 2010-06-16
张仲伦
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the alkali recovery method for processing black liquor has huge investment, high maintenance and operation costs, and the combustion process causes the emission of greenhouse gas carbon dioxide and produces a large amount of secondary pollutants—white mud; the purity of lignin separated by acid analysis is low, and waste Acid is easy to cause secondary pollution. When the precipitated lignin particles are small, especially when there is interference from silica gel in straw pulp, reed pulp, and bagasse pulp, it is difficult to wash, filter, and separate lignin; Lignin has the disadvantages of introducing impurities (flocculant), large amount of resin, loose lignin precipitation, and difficult separation operation; membrane separation method has the disadvantages of small water flux, low retention rate, small processing capacity, chroma, CODcr, BOD 5 The removal rate still needs to be improved; the biological method is generally only suitable for the treatment of CODcr and BOD 5 Relatively low dilute black liquor, high operating costs, strict operating conditions, and available lignin, polysaccharides and other organic substances are basically biochemically decomposed, and resources cannot be effectively utilized

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The concentrated bagasse black liquor with a standard Baumé degree of 28Be° has a solid content of 41.5%, of which lignin content is 12%, inorganic matter is 14%, polysaccharides are 15.9%, PH value is 13.4, COD cr Value is 440000mg / l, BOD 5 Value is 125200mg / l (PH value, COD cr , BOD 5 All are measured after dilution one hundred times). Add 37% industrial formaldehyde at the ratio of lignin to formaldehyde molar ratio of 1:1, and react at 80°C for 3 hours. The rotation speed of the stirring motor is 17 rpm, and formaldehyde is added dropwise at a constant speed after the temperature rise starts, and the dropwise addition is completed within 1.5 hours.

[0019] Sulfuric acid with a concentration of 38% is added to the black liquor after the polycondensation reaction until the pH value is reduced to 3 to precipitate the lignin in the black liquor to form a lignin suspension. Sulfuric acid was added at a uniform speed within 1 hour, and the speed of the stirring motor was 17...

Embodiment 2

[0025] The concentrated wood pulp black liquor with a standard Baume degree of 18Be°, the solid content is 26.3%, of which the lignin content is 8.1%, the inorganic matter is 8.0%, the glycan is 10.2%, the PH value is 13.2, and COD cr Value is 290000mg / l, BOD 5 Value is 82100mg / l (PH value, COD cr , BOD 5 All are measured after dilution one hundred times). Add 37% industrial formaldehyde at the ratio of lignin to formaldehyde molar ratio of 1:0.1, and react at 70°C for 4 hours. The rotation speed of the stirring motor is 17 rpm, and formaldehyde is added dropwise at a constant speed after the temperature rise starts, and the dropwise addition is completed within 2 hours.

[0026] Add CO into the black liquor after the polycondensation reaction 2 Flue gas until the pH value drops to 6. The lignin suspension was aged at about 50°C for 1 hour, and then allowed to stand for 12 hours. The lignin in the black liquor is precipitated to form a suspension of lignin. The black liquor is ...

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Abstract

The invention discloses a processing method of paper-making pulping black liquor, and the method comprises polycondensation, acid precipitation, aging, precipitation, solid-liquid separation and drying of the pulping paper-making black liquor, and in the black liquor, the solid phase which mainly comprises lignin and the liquid phase which mainly comprises sodium salt solution are separated; and the Baume degree of the black liquor is larger than or equal to 15 Be degrees. The method has simple process, low cost and wide application range. The obtained lignin can be used as multiple industrial and agricultural raw materials; the chroma, CODcr and BOD5 of the obtained liquid phase are greatly reduced.

Description

Technical field [0001] The invention relates to the field of chemical engineering, in particular to a method for treating black liquor in papermaking and pulping. Background technique [0002] The plant raw materials used for papermaking are mainly composed of cellulose, lignin and polysaccharides. Among them, cellulose is the effective component of papermaking, accounting for about 40% of the plant raw materials; lignin and polysaccharides accounting for about 60% of the plant raw materials %, it is separated into waste liquid in the papermaking pulping process. The papermaking waste liquid formed by alkaline pulping is black liquor, which includes separated lignin, polysaccharides, and residual alkali and water. The black liquor from different plant sources has a CODcr concentration between 15,000 and 500,000 mg / L, and lignin and its degradation products account for about 50% of the total CODcr. If the black liquor is directly discharged without effective treatment, it will n...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C11/04
Inventor 张仲伦何孟群
Owner 张仲伦
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